1. Field of the Invention
The present invention relates to a transfer device that is preferably provided between a semiconductor manufacturing device and an aisle, and used for a shelf that temporarily stores an object containing a substrate necessary to manufacture a semiconductor and changes a storage area for the object within the shelf.
2. Description of the Related Art
When substrates such as a glass substrate and a silicon substrate are brought from one location to a semiconductor manufacturing device and when processed substrates are carried to another location, a conventional scheme utilizes a box, referred to as a container, to contain multiple substrates and transfers the container. In transferring the container, an overhead transferring vehicle which travels near the ceiling is used to save space in a semiconductor manufacturing factory.
The container has to be temporarily stored, depending on how a preceding process and a supplemental process progress in the manufacturing process of semiconductors. In order to store the container, a shelf for storing the container is provided above a loader and an unloader for the semiconductor manufacturing device. The semiconductor manufacturing device has a transfer device. The transfer device can automatically transfer an appropriate container from the shelf to the loader when the substrates are ready to be processed. The transfer device can also automatically transfer from the unloader to the shelf a container containing processed substrates.
In order to save space, a semiconductor manufacturing factory has semiconductor manufacturing devices on both sides of an aisle across from each other. The loader and the unloader are provided between the semiconductor manufacturing device and the aisle. The transfer device is provided between the loader/unloader and the aisle.
Japanese Unexamined Patent Application Publication No. 2001-298069 discloses a transfer device and a shelf. The shelf in Japanese Unexamined Patent Application Publication No. 2001-298069 has horizontal and vertical aisles so that a container held by the transfer device can move inside the shelf. This structure saves as much space as possible. Moreover, the transfer device has rails each used for moving a holding unit, which holds a container, in the vertical direction and the horizontal direction. The rails are attached to the shelf. This structure provides aisles that are as wide as possible.
As recent substrates are becoming larger, a container for containing the substrates is becoming heavier. Such a trend requires a transfer device to be stiffer.